Electrostatic deposition

Miscellaneous Methods. Powdered metals such as aluminum, chromium, nickel, and copper, along with various aHoys, can be appHed to parts by electrostatic deposition. The metal strip containing the attached powdered metal must be further processed by cold rolling and sintering to compact and bond the metal powder. 

The use of nylon-11 for powder coatings or dry coatings (qv) has been developed in response to a growing concern for the environment (44) (see Coating PROCESSES, powder technology). Electrostatic deposition allows thin films to be appHed to metal substrates. Once the powder is appHed, it must be melted and coalesced into a continuous plastic film. Eorced draft or irradiant ovens are used for fusion, and because no polymerization or cross-linkage are required for curing, coated objects can be processed quickly and air-cooled (45). 

The basic operations in dust collection by any device are (1) separation of the gas-borne particles from the gas stream by deposition on a collecting surface (2) retention of the deposit on the surface and (3) removal of the deposit from the surface for recovery or disposal. The separation step requires (1) application of a force that produces a differential motion of a particle relative to the gas and (2) a gas retention time sufficient for the particle to migrate to the coUecting surface. The principal mechanisms of aerosol deposition that are apphed in dust collectors are (1) gravitational deposition, (2) flow-line interception, (3) inertial deposition, (4) diffusional deposition, and (5) electrostatic deposition. Thermal deposition is only a minor factor in practical dust-collectiou equipment because the thermophoretic force is small. Table 17-2 lists these six mechanisms and presents the characteristic... 

The principal mechanisms of disposition in dust collectors are (1) gravitational deposition, (2) flow-line interception, (3) inertial deposition, (4) diffusional deposition, and (5) electrostatic deposition. During the initial operating period, particle deposition takes place mainly by inertial and flow-line interception, diffusion, and gravity. Once the dust layer has been fully established, sieving is probably the dominant deposition mechanism. 

A series of other removal processes, such as filtration, diffu-sional plateout and electrostatic deposition, may, however, be effective in the case of the airborne radon progeny, and since the major part of the radiological exposure in a given environment connected with radon is due to the radon progeny rather than to the radon gas itself, it may be of interest to look into these processes... 

Polyamidoamine (PAMAM) dendrimers (G3.5-G10) were used by Tsukruk et al. [25,26] to fabricate self-assembled monolayers by an electrostatic deposition techniques [27],... 

A detailed analysis of the various mechanisms of electrostatic deposition has been presented by Kraemer (K6), Kraemer and Johnstone (K7), and Dawkins (D3). 

For electrostatic deposition or electrostatic powdering, the scheme is slightly different ... 

Fabrication of organic thin films based on sponfaneous molecular assembly has been considered as one of fhe powerful approaches to create novel supramolecular systems. In this context, multilayer films were fabricated by layer-by-layer electrostatic deposition techniques based on the electrostatic interaction between dsDNA and the positively charged polymer poly(diallyldimethylammonium chloride) (PDDA) on GC surfaces. A uniform assembly of PDDA/DNA multilayer films was achieved, based on the adsorption of the negatively charged DNA molecules on the positively charged substrate [55]. 

Anjier, J. L. et al., Chamber Lining by Electrostatic Deposition, AIChE,... 

Layer-by-layer electrostatic deposition of biopolymers at interface of emulsion droplets Polyelectrolyte capsules microparticles with novel functionality and triggered release multiple layers around oil droplets exhibiting improved stability towards environmental stresses (temperature, ionic strength, pH, freezing, dehydration) McClements, 2005, 2006 Sanguansri and Augustin, 2006... 

Aoki, T., Decker, E.A., McClements, D.J. (2005). Influence of environmental stresses on stability of O/W emulsions containing droplets stabilized by multilayered membranes produced by a layer-by-layer electrostatic deposition technique. Food Hydrocolloids, 19, 209-220. 

Structural Features of Electrostatically Deposited Multilayer Assemblies... 

Nanoscale assembly Self-assembling micellar structures [113,114] Bio-self-assembly and aggregation [115,116] Nanomanipulation [117,118] Soft lithography [119,120] Molecular imprinting [121,122] Layer-by-layer electrostatic deposition [123,124] Chemical vapor deposition [125]... 

Electrostatic deposition and other mechanisms of capture such as diffu-sional deposition and thermal deposition will not be discussed in this section, as they affect only the smallest particles, which mi t remain stuck to the pins until being knocked off by large colliding particles. 

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